The present invention relates to a novel anti-inflammatory and anti-allergic compound of the androstane series and to processes for its preparation. The present invention also relates to pharmaceutical formulations containing the compound and to therapeutic uses thereof, particularly for the treatment of inflammatory and allergic conditions.
Glucocorticoids which have anti-inflammatory properties are known and are widely used for the treatment of inflammatory disorders or diseases such as asthma and rhinitis. For example, U.S. Pat. No. 4,335,121 discloses 6xcex1, 9xcex1-Difluoro-17xcex1-(1-oxopropoxy)-11xcex2-hydroxy-16xcex1-methyl-3-oxo-androsta-1,4-diene-17xcex2-carbothioic acid S-fluoromethyl ester (known by the generic name of fluticasone propionate) and derivatives thereof. The use of glucocorticoids generally, and especially in children, has been limited in some quarters by concerns over potential side effects. The side effects that are feared with glucocorticoids include suppression of the Hypothalamic-Pituitary-Adrenal (HPA) axis, effects on bone growth in children and on bone density in the elderly, ocular complications (cataract formation and glaucoma) and skin atrophy. Certain glucocorticoid compounds also have complex paths of metabolism wherein the production of active metabolites may make the pharmacodynamics and pharmacokinetics of such compounds difficult to understand. Whilst the modern steroids are very much safer than those originally introduced, it remains an object of research to produce new molecules which have excellent anti-inflammatory properties, with predictable pharmacokinetic and pharmacodynamic properties, with an attractive side effect profile, and with a convenient treatment regime.
We have now identified a novel glucocorticoid compound which substantially meets these objectives.
Thus, according to one aspect of the invention, there is provided a compound of formula (I) 
and solvates thereof.
The chemical name of the compound of formula (I) is 6xcex1, 9xcex1-Difluoro-17xcex1-[(2-furanylcarbonyl)oxy]-11xcex2-hydroxy-16xcex1-methyl-3-oxo-androsta-1,4-diene-17xcex2-carbothioic acid S-fluoromethyl ester.
References hereinafter to the compound according to the invention include both the compound of formula (I) and solvates thereof, particularly pharmaceutically acceptable solvates.
The compound of formula (I) has potentially beneficial anti-inflammatory or anti-allergic effects, particularly upon topical administration, demonstrated by, for example, its ability to bind to the glucocorticoid receptor and to illicit a response via that receptor, with long acting effect. Hence, the compound of formula (I) is useful in the treatment of inflammatory and/or allergic disorders, especially in once-per-day therapy.
Compound (I) undergoes highly efficient hepatic metabolism to yield the 17-xcex2carboxylic acid (X) as the sole major metabolite in rat and human in vitro systems. This metabolite has been synthesised and demonstrated to be  greater than 1000 fold less active than the parent compound in in vitro functional glucocorticoid assays. 
This efficient hepatic metabolism is reflected by in vivo data in the rat, which have demonstrated plasma clearance at a rate approaching hepatic blood flow and an oral bioavailability of  less than 1%, consistent with extensive first-pass metabolism.
In vitro metabolism studies in human hepatocytes have demonstrated that compound (I) is metabolised in an identical manner to fluticasone propionate but that conversion of (I) to the inactive acid metabolite occurs approximately 5-fold more rapidly than with fluticasone propionate. This very efficient hepatic inactivation would be expected to minimise systemic exposure in man leading to an improved safety profile.
Inhaled steroids are also absorbed through the lung and this route of absorption makes a significant contribution to systemic exposure. Reduced lung absorption could therefore provide an improved safety profile. Studies with compound of formula (I) have shown significantly lower exposure to compound of formula (I) than with fluticasone propionate after dry powder delivery to the lungs of anaesthetised pigs.
An improved safety profile is believed to allow the compound of formula (I) to demonstrate the desired anti-inflammatory effects when administered once-per day. Once-per-day dosing is considered to be significantly more convenient to patients than the twice-per day dosing regime that is normally employed for fluticasone propionate.
Examples of disease states in which the compound of the invention has utility include skin diseases such as eczema, psoriasis, allergic dermatitis, neurodermatitis, pruritis and hypersensitivity reactions; inflammatory conditions of the nose, throat or lungs such as asthma (including allergen-induced asthmatic reactions), rhinitis (including hayfever), nasal polyps, chronic obstructive pulmonary disease (COPD), interstitial lung disease, and fibrosis; inflammatory bowel conditions such as ulcerative colitis and Crohn""s disease; and auto-immune diseases such as rheumatoid arthritis.
The compound of the invention may also have use in the treatment of conjunctiva and conjunctivitis.
The compound of formula (I) and solvates thereof is expected to be most useful in the treatment of inflammatory disorders of the respiratory tract eg asthma and COPD, particularly asthma.
It will be appreciated by those skilled in the art that reference herein to treatment extends to prophylaxis as well as the treatment of established conditions.
As mentioned above, the compound of formula (I) is useful in human or veterinary medicine, in particular as an anti-inflammatory and anti-allergic agent.
There is thus provided as a further aspect of the invention the compound of formula (I) or a physiologically acceptable solvate thereof for use in human or veterinary medicine, particularly in the treatment of patients with inflammatory and/or allergic conditions, especially for treatment once-per-day.
According to another aspect of the invention, there is provided the use of the compound of formula (I) or physiologically acceptable solvate thereof for the manufacture of a medicament for the treatment of patients with inflammatory and/or allergic conditions, especially for treatment once-per-day.
In a further or alternative aspect, there is provided a method for the treatment of a human or animal subject with an inflammatory and/or allergic condition, which method comprises administering to said human or animal subject an effective amount of the compound of formula (I) or physiologically acceptable solvate thereof, especially for administration once-per-day.
The compound according to the invention may be formulated for administration in any convenient way, and the invention therefore also includes within its scope pharmaceutical compositions comprising the compound of formula (I) or a physiologically acceptable solvate thereof together, if desirable, in admixture with one or more physiologically acceptable diluents or carriers. Pharmaceutical compositions suitable for once-per-day administration are of particular interest.
Further, there is provided a process for the preparation of such pharmaceutical compositions which comprises mixing the ingredients.
The compound according to the invention may, for example, be formulated for oral, buccal, sublingual, parenteral, local or rectal administration, especially local administration.
Local administration as used herein, includes administration by insufflation and inhalation. Examples of various types of preparation for local administration include ointments, lotions, creams, gels, foams, preparations for delivery by transdermal patches, powders, sprays, aerosols, capsules or cartridges for use in an inhaler or insufflator or drops (eg eye or nose drops), solutions/suspensions for nebulisation, suppositories, pessaries, retention enemas and chewable or suckable tablets or pellets (eg for the treatment of aphthous ulcers) or liposome or microencapsulation preparations.
Advantageously compositions for topical administration to the lung include dry powder compositions and spray compositions.
Dry powder compositions for topical delivery to the lung by inhalation may, for example, be presented in capsules and cartridges for use in an inhaler or insufflator of, for example, gelatine. Formulations generally contain a powder mix for inhalation of the compound of the invention and a suitable powder base (carrier substance) such as lactose or starch. Use of lactose is preferred. Each capsule or cartridge may generally contain between 20 xcexcg-10 mg of the compound of formula (I) optionally in combination with another therapeutically active ingredient. Alternatively, the compound of the invention may be presented without excipients. Packaging of the formulation may be suitable for unit dose or multi-dose delivery. In the case of multi-dose delivery, the formulation can be pre-metered (eg as in Diskus, see GB 2242134 or Diskhaler, see GB 2178965, 2129691 and 2169265) or metered in use (eg as in Turbuhaler, see EP 69715). An example of a unit-dose device is Rotahaler (see GB 2064336). The Diskus inhalation device comprises an elongate strip formed from a base sheet having a plurality of recesses spaced along its length and a lid sheet hermetically but peelably sealed thereto to define a plurality of containers, each container having therein an inhalable formulation containing a compound of formula (I) optionally in combination with another therapeutically active ingredient preferably combined with lactose. Preferably, the strip is sufficiently flexible to be wound into a roll. The lid sheet and base sheet will preferably have leading end portions which are not sealed to one another and at least one of the said leading end portions is constructed to be attached to a winding means. Also, preferably the hermetic seal between the base and lid sheets extends over their whole width. The lid sheet may preferably be peeled from the base sheet in a longitudinal direction from a first end of the said base sheet.
Spray compositions for topical delivery to the lung by inhalation may for example be formulated as aqueous solutions or suspensions or as aerosols delivered from pressurised packs, such as a metered dose inhaler, with the use of a suitable liquefied propellant. Aerosol compositions suitable for inhalation can be either a suspension or a solution and generally contain the compound of formula (I) optionally in combination with another therapeutically active ingredient and a suitable propellant such as a fluorocarbon or hydrogen-containing chlorofluorocarbon or mixtures thereof, particularly hydrofluoroalkanes, especially 1,1,1,2-tetrafluoroethane, 1,1,1,2,3,3,3-heptafluoro-n-propane or a mixture thereof. The aerosol composition may optionally contain additional formulation excipients well known in the art such as surfactants eg oleic acid or lecithin and cosolvents eg ethanol. One example formulation is excipient free and consists essentially of (eg consists of) compound of formula (I) (preferably in unsolvated form eg as Form 1) (optionally together with a further active ingredient) and a propellant selected from 1,1,1,2-tetrafluoroethane, 1,1,1,2,3,3,3-heptafluoro-n-propane and mixture thereof. Another example formulation comprises particulate compound of formula (I), a propellant selected from 1,1,1,2-tetrafluoroethane, 1,1,1,2,3,3,3-heptafluoro-n-propane and mixture thereof and a suspending agent which is soluble in the propellant eg an oligolactic acid or derivative thereof as described in WO94/21229. The preferred propellant is 1,1,1,2-tetrafluoroethane. As noted elsewhere in this specification, compound of formula (I) does not appear to form a solvate with 1,1,1,2-tetrafluoroethane. Pressurised formulations will generally be retained in a canister (eg an aluminium canister) closed with a valve (eg a metering valve) and fitted into an actuator provided with a mouthpiece.
Pressurised aerosol formulations preferably do not comprise particulate medicament, a propellant and a stabiliser comprising a water addition (i.e. water added in addition to nascent formulation water). Pressurised aerosol formulations also preferably do not comprise particulate medicament, a propellant and a stabiliser comprising an amino acid, a derivative thereof or a mixture thereof.
Medicaments for administration by inhalation desirably have a controlled particle size. The optimum particle size for inhalation into the bronchial system is usually 1-10 xcexcm, preferably 2-5 xcexcm. Particles having a size above 20 xcexcm are generally too large when inhaled to reach the small airways. To achieve these particle sizes the particles of compound of formula (I) (and any further therapeutically active ingredient) as produced may be size reduced by conventional means eg by micronisation. The desired fraction may be separated out by air classification or sieving. Preferably, the particles will be crystalline, prepared for example by a process which comprises mixing in a continuous flow cell in the presence of ultrasonic radiation a flowing solution of compound of formula (I) as medicament in a liquid solvent with a flowing liquid antisolvent for said medicament (eg as described in International Patent Application PCT/GB99/04368) or else by a process which comprises admitting a stream of solution of the substance in a liquid solvent and a stream of liquid antisolvent for said substance tangentially into a cylindrical mixing chamber having an axial outlet port such that said streams are thereby intimately mixed through formation of a vortex and precipitation of crystalline particles of the substance is thereby caused (eg as described in International Patent Application PCT/GB00/04327). When an excipient such as lactose is employed, generally, the particle size of the excipient will be much greater than the inhaled medicament within the present invention. When the excipient is lactose it will typically be present as milled lactose, wherein not more than 85% of lactose particles will have a MMD of 60-90 xcexcm and not less than 15% will have a MMD of less than 15 xcexcm.
Formulations for administration topically to the nose (eg for the treatment of rhinitis) include pressurised aerosol formulations and aqueous formulations administered to the nose by pressurised pump. Formulations which are non-pressurised and adapted to be administered topically to the nasal cavity are of particular interest. The formulation preferably contains water as the diluent or carrier for this purpose. Aqueous formulations for administration to the lung or nose may be provided with conventional excipients such as buffering agents, tonicity modifying agents and the like. Aqueous formulations may also be administered to the nose by nebulisation.
Other possible presentations include the following:
Ointments, creams and gels, may, for example, be formulated with an aqueous or oily base with the addition of suitable thickening and/or gelling agent and/or solvents. Such bases may thus, for example, include water and/or an oil such as liquid paraffin or a vegetable oil such as arachis oil or castor oil, or a solvent such as polyethylene glycol. Thickening agents and gelling agents which may be used according to the nature of the base include soft paraffin, aluminium stearate, cetostearyl alcohol, polyethylene glycols, woolfat, beeswax, carboxypolymethylene and cellulose derivatives, and/or glyceryl monostearate and/or non-ionic emulsifying agents.
Lotions may be formulated with an aqueous or oily base and will in general also contain one or more emulsifying agents, stabilising agents, dispersing agents, suspending agents or thickening agents.
Powders for external application may be formed with the aid of any suitable powder base (carrier substance), for example, talc, lactose or starch. Drops may be formulated with an aqueous or non-aqueous base also comprising one or more dispersing agents, solubilising agents, suspending agents or preservatives.
If appropriate, the formulations of the invention may be buffered by the addition of suitable buffering agents.
The proportion of the active compound of formula (I) in the local compositions according to the invention depends on the precise type of formulation to be prepared but will generally be within the range of from 0.001 to 10% by weight. Generally, however for most types of preparations advantageously the proportion used will be within the range of from 0.005 to 1% and preferably 0.01 to 0.5%. However, in powders for inhalation or insufflation the proportion used will usually be within the range of from 0.1 to 5%.
Aerosol formulations are preferably arranged so that each metered dose or xe2x80x9cpuffxe2x80x9d of aerosol contains 1 xcexcg-2000 xcexcg eg 20 xcexcg-2000 xcexcg, preferably about 20 xcexcg-500 xcexcg of a compound of formula (I) optionally in combination with another therapeutically active ingredient. Administration may be once daily or several times daily, for example 2, 3, 4 or 8 times, giving for example 1, 2 or 3 doses each time. Preferably the compound of formula (I) is delivered once or twice daily, more preferably once-per-day. The overall daily dose with an aerosol will typically be within the range 10 xcexcg-10 mg eg 100 xcexcg-10 mg preferably, 200 xcexcg-2000 xcexcg.
Since the compound of formula (I) is long-acting, preferably the compound will be delivered once-per-day and the dose will be selected so that the compound has a therapeutic effect in the treatment of respiratory disorders (eg asthma or COPD, particularly asthma) over 24 hours or more.
Topical preparations may be administered by one or more applications per day to the affected area; over skin areas occlusive dressings may advantageously be used. Continuous or prolonged delivery may be achieved by an adhesive reservoir system.
For internal administration the compound according to the invention may, for example, be formulated in conventional manner for oral, parenteral or rectal administration. Formulations for oral administration include syrups, elixirs, powders, granules, tablets and capsules which typically contain conventional excipients such as binding agents, fillers, lubricants, disintegrants, wetting agents, suspending agents, emulsifying agents, preservatives, buffer salts, flavouring, colouring and/or sweetening agents as appropriate. Dosage unit forms are, however, preferred as described below.
Preferred forms of preparation for internal administration are dosage unit forms i.e. tablets and capsules. Such dosage unit forms contain from 0.1 mg to 20 mg preferably from 2.5 to 10 mg of the compound of the invention.
The compound according to the invention may in general may be given by internal administration in cases where systemic adreno-cortical therapy is indicated.
In general terms preparations, for internal administration may contain from 0.05 to 10% of the active ingredient dependent upon the type of preparation involved. The daily dose may vary from 0.1 mg to 60 mg, eg 5-30 mg, dependent on the condition being treated, and the duration of treatment desired.
Slow release or enteric coated formulations may be advantageous, particularly for the treatment of inflammatory bowel disorders.
The pharmaceutical compositions according to the invention may also be used in combination with another therapeutically active agent, for example, a xcex22 adrenoreceptor agonist, an anti-histamine or an anti-allergic. The invention thus provides, in a further aspect, a combination comprising the compound of formula (I) or a physiologically acceptable solvate thereof together with another therapeutically active agent, for example, a xcex22-adrenoreceptor agonist, an anti-histamine or an anti-allergic.
Examples of xcex22-adrenoreceptor agonists include salmeterol (eg as racemate or a single enantiomer such as the R-enantiomer), salbutamol, formoterol, salmefamol, fenoterol or terbutaline and salts thereof, for example the xinafoate salt of salmeterol, the sulphate salt or free base of salbutamol or the fumarate salt of formoterol. Pharmaceutical compositions employing combinations with long-acting xcex22-adrenoreceptor agonists (eg salmeterol and salts thereof) are particularly preferred, especially those which have a therapeutic effect (eg in the treatment of asthma or COPD, particularly asthma) over 24 hours or more.
Since the compound of formula (I) is long-acting, preferably the composition comprising the compound of formula (I) and the long-acting xcex22-adrenoreceptor agonists will be delivered once-per-day and the dose of each will be selected so that the composition has a therapeutic effect in the treatment of respiratory disorders effect (eg in the treatment of asthma or COPD, particularly asthma) over 24 hours or more.
Examples of anti-histamines include methapyrilene or loratadine.
Other suitable combinations include, for example, other anti-inflammatory agents eg NSAIDs (eg sodium cromoglycate, nedocromil sodium, PDE4 inhibitors, leukotriene antagonists, iNOS inhibitors, tryptase and elastase inhibitors, beta-2 integrin antagonists and adenosine 2a agonists)) or antiinfective agents (eg antibiotics, antivirals).
Also of particular interest is use of the compound of formula (I) in combination with a phosphodiesterase 4 (PDE4) inhibitor. The PDE4-specific inhibitor useful in this aspect of the invention may be any compound that is known to inhibit the PDE4 enzyme or which is discovered to act as a PDE4 inhibitor, and which are only PDE4 inhibitors, not compounds which inhibit other members of the PDE family as well as PDE4. Generally it is preferred to use a PDE4 inhibitor which has an IC50 ratio of about 0.1 or greater as regards the IC50 for the PDE4 catalytic form which binds rolipram with a high affinity divided by the IC50 for the form which binds rolipram with a low affinity. For the purposes of this disclosure, the cAMP catalytic site which binds R and S rolipram with a low affinity is denominated the xe2x80x9clow affinityxe2x80x9d binding site (LPDE 4) and the other form of this catalytic site which binds rolipram with a high affinity is denominated the xe2x80x9chigh affinityxe2x80x9d binding site (HPDE 4). This term xe2x80x9cHPDE4xe2x80x9d should not be confused with the term xe2x80x9chPDE4xe2x80x9d which is used to denote human PDE4. Initial experiments were conducted to establish and validate a [3H]-rolipram binding assay. Details of this work are given in the Binding Assays described in detail below.
The preferred PDE4 inhibitors of use in this invention will be those compounds which have a salutary therapeutic ratio, i.e., compounds which preferentially inhibit cAMP catalytic activity where the enzyme is in the form that binds rolipram with a low affinity, thereby reducing the side effects which apparently are linked to inhibiting the form which binds rolipram with a high affinity. Another way to state this is that the preferred compounds will have an IC50 ratio of about 0.1 or greater as regards the IC50 for the PDE4 catalytic form which binds rolipram with a high affinity divided by the IC50 for the form which binds rolipram with a low affinity.
A further refinement of this standard is that of one wherein the PDE4 inhibitor has an IC50 ratio of about 0.1 or greater; said ratio is the ratio of the IC50 value for competing with the binding of 1 nM of [3H]R-rolipram to a form of PDE4 which binds rolipram with a high affinity over the IC50 value for inhibiting the PDE4 catalytic activity of a form which binds rolipram with a low affinity using 1 xcexcM[3H]-cAMP as the substrate.
Examples of useful PDE4 inhibitors are:
(R)-(+)-1-(4-bromobenzyl)-4-[(3-cyclopentyloxy)-4-methoxyphenyl]-2-pyrrolidone;
(R)-(+)-1-(4-bromobenzyl)-4-[(3-cyclopentyloxy)-4-methoxyphenyl]-2-pyrrolidone;
3-(cyclopentyloxy-4-methoxyphenyl)-1-(4-Nxe2x80x2-[N2-cyano-S-methyl-isothioureido]benzyl)-2-pyrrolidone;
cis 4-cyano-4-(3-cyclopentyloxy-4-methoxyphenyl)cyclohexan-1-carboxylic acid];
cis-[4-cyano-4-(3-cyclopropylmethoxy-4-difluoromethoxyphenyl)cyclohexan-1-ol];
(R)-(+)-ethyl [4-(3-cyclopentyloxy-4-methoxyphenyl)pyrrolidine-2-ylidene]acetate; and
(S)-(xe2x88x92)-ethyl [4-(3-cyclopentyloxy-4-methoxyphenyl)pyrrolidine-2-ylidene]acetate.
Most preferred are those PDE4 inhibitors which have an IC50 ratio of greater than 0.5, and particularly those compounds having a ratio of greater than 1.0. Preferred compounds are cis 4-cyano-4-(3-cyclopentyloxy-4-methoxyphenyl)cyclohexan-1-carboxylic acid, 2-carbomethoxy-4-cyano-4-(3-cyclopropylmethoxy-4-difluoromethoxyphenyl)cyclohexan-1-one and cis-[4-cyano-4-(3-cyclopropylmethoxy-4-difluoromethoxyphenyl)cyclohexan-1-ol]; these are examples of compounds which bind preferentially to the low affinity binding site and which have an IC50 ratio of 0.1 or greater.
Other compounds of interest include:
Compounds set out in U.S. Pat. No. 5,552,438 issued Sep. 3, 1996; this patent and the compounds it discloses are incorporated herein in full by reference. The compound of particular interest, which is disclosed in U.S. Pat. No. 5,552,438, is cis-4-cyano-4-[3-(cyclopentyloxy)-4-methoxyphenyl]cyclohexane-1-carboxylic acid (also known as cilomalast) and its salts, esters, pro-drugs or physical forms;
AWD-12-281 from Astra (Hofgen, N. et al. 15th EFMC Int Symp Med Chem (September 6-10, Edinburgh) 1998, Abst P.98); a 9-benzyladenine derivative nominated NCS-613 (INSERM); D-4418 from Chiroscience and Schering-Plough; a benzodiazepine PDE4 inhibitor identified as Cl-1018 (PD-168787; Parke-Davis/Warner-Lambert); a benzodioxole derivative Kyowa Hakko disclosed in WO 9916766; V-11294A from Napp (Landells, L. J. et al. Eur Resp J [Annu Cong Eur Resp Soc (September 19-23, Geneva) 1998] 1998, 12(Suppl. 28): Abst P2393); roflumilast (CAS reference No 162401-32-3) and a pthalazinone (WO 9947505) from Byk-Gulden; or a compound identified as T-440 (Tanabe Seiyaku; Fuji, K. et al. J Pharmacol Exp Ther, 1998, 284(1): 162).
Phosphodiesterase and Rolipram Binding Assays
Assay Method 1A
Isolated human monocyte PDE4 and hrPDE (human recombinant PDE4) was determined to exist primarily in the low affinity form. Hence, the activity of test compounds against the low affinity form of PDE4 can be assessed using standard assays for PDE4 catalytic activity employing 1 xcexcM [3H]cAMP as a substrate (Torphy et al., J. of Biol. Chem., Vol. 267, No. 3 pp 1798-1804, 1992).
Rat brain high speed supernatants were used as a source of protein and both enantiomers of [3H]-rolipram were prepared to a specific activity of 25.6 Ci/mmol. Standard assay conditions were modified from the published procedure to be identical to the PDE assay conditions, except for the last of the cAMP: 50 mM Tris HCl (pH 7.5), 5 mM MgCl2, 50 xcexcM 5xe2x80x2-AMP and 1 nM of [3H]-rolipram (Torphy et al., J. of Biol. Chem., Vol. 267, No. 3 pp 1798-1804, 1992). The assay was run for 1 hour at 30xc2x0 C. The reaction was terminated and bound ligand was separated from free ligand using a Brandel cell harvester. Competition for the high affinity binding site was assessed under conditions that were identical to those used for measuring low affinity PDE activity, expect that [3H]-cAMP was not present.
Assay Method 1B
Measurement of Phosphodiesterase Activity
PDE activity was assayed using a [3H]cAMP SPA or [3H]cGMP SPA enzyme assay as described by the supplier (Amersham Life Sciences). The reactions were conducted in 96-well plates at room temperature, in 0.1 ml of reaction buffer containing (final concentrations): 50 mM Tris-HCl, pH 7.5, 8.3 mM MgCl2, 1.7 mM EGTA, [3H]cAMP or [3H] cGMP (approximately 2000 dpm/pmol), enzyme and various concentrations of the inhibitors. The assay was allowed to proceed for 1 hr and was terminated by adding 50 xcexcl of SPA yttrium silicate beads in the presence of zinc sulfate. The plates were shaken and allowed to stand at room temperature for 20 min. Radiolabeled product formation was assessed by scintillation spectrometry.
[3H]R-Rolipram Binding Assay
The [3H]R-rolipram binding assay was performed by modification of the method of Schneider and co-workers, see Nicholson, et al., Trends Pharmacol. Sci., Vol. 12, pp. 19-27 (1991) and McHale et al., Mol. Pharmacol., Vol. 39, 109-113 (1991). R-Rolipram binds to the catalytic site of PDE4 see Torphy et al., Mol. Pharmacol., Vol. 39, pp. 376-384 (1991). Consequently, competition for [3H]R-rolipram binding provides an independent confirmation of the PDE4 inhibitor potencies of unlabeled competitors. The assay was performed at 30xc2x0 C. for 1 hr in 0.5 xcexcl buffer containing (final concentrations): 50 mM Tris-HCl, pH 7.5, 5 mM MgCl2, 0.05% bovine serum albumin, 2 nM [3H]R-rolipram (5.7xc3x97104 dpm/pmol) and various concentrations of non-radiolabeled inhibitors. The reaction was stopped by the addition of 2.5 ml of ice-cold reaction buffer (without [3H]-R-rolipram) and rapid vacuum filtration (Brandel Cell Harvester) through Whatman GF/B filters that had been soaked in 0.3% polyethylenimine. The filters were washed with an additional 7.5 ml of cold buffer, dried, and counted via liquid scintillation spectrometry.
The invention thus provides, in a further aspect, a combination comprising the compound of formula (I) or a physiologically acceptable solvate thereof together with a PDE4 inhibitor.
The combination referred to above may conveniently be presented for use in the form of a pharmaceutical formulation and thus pharmaceutical formulations comprising a combination as defined above together with a physiologically acceptable diluent or carrier represent a further aspect of the invention.
The compound according to the invention in combination with another therapeutically active ingredient as described above may be formulated for administration in any convenient way, and the invention therefore also includes within its scope pharmaceutical compositions comprising the compound of formula (I) or a physiologically acceptable solvate thereof in combination with another therapeutically active ingredient together, if desirable, in admixture with one or more physiologically acceptable diluents or carriers. The preferred route of administration for inflammatory disorders of the respiratory tract will generally be administration by inhalation.
Further, there is provided a process for the preparation of such pharmaceutical compositions which comprises mixing the ingredients.
The individual compounds of such combinations may be administered either sequentially in separate pharmaceutical compositions as well as simultaneously in combined pharmaceutical formulations. Appropriate doses of known therapeutic agents will be readily appreciated by those skilled in the art.
Surprisingly, the compound of formula (I) has demonstrated a significant propensity to form solvates with commonly used organic solvents. Such solvates are essentially stoichiometric eg the ratio of compound of formula (I) to solvent is close to 1:1 eg according to Applicant""s analysis has been determined to be in the range 0.95-1.05:1. For example, we have prepared solvates with solvents such as acetone, dimethylformamide (DMF), dimethylacetamide (DMAc), tetrahydrofuran (THF), N-methyl-2-pyrrolidone, isopropanol and methylethylketone. The solvation of compound of formula (I) is not predictable however since we have found that even though it does form a solvate with isopropanol it does not appear to form a solvate with ethanol or methanol. Furthermore it does not appear to form a solvate with 1,1,1,2-tetrafluoroethane, ethylacetate, methylacetate, toluene, methylisobutylketone (MIBK) or water either. However due to the toxicity of many organic solvents it has been necessary to develop special final stage processing conditions (discussed later) in order to permit the compound of formula (I) to be produced in unsolvated form. Thus according to another aspect of the invention there is provided a compound of formula (I) in unsolvated form.
Surprisingly we have also discovered that the compound of formula (I) in unsolvated form may exist in a number of polymorphic forms. Specifically we have identified polymorphic forms which may be distinguished by means of X-Ray Powder Diffraction (XRPD) which we have named as Form 1, Form 2 and Form 3. Form 3 appears to be an unstable minor polymorphic modification of Form 2.
Broadly speaking the Forms are characterised in their XRPD profiles as follows:
Form 1: Peak at around 18.9 degrees 2Theta
Form 2: Peaks at around 18.4 and 21.5 degrees 2Theta.
Form 3: Peaks at around 18.6 and 19.2 degrees 2Theta.
Within the range 21-23 degrees 2Theta Form 3 shows a single peak whereas Form 2 shows a pair of peaks. A peak at 7 degrees 2Theta is present in all cases however it is present at much higher intensity in the case of Forms 2 and 3 than is the case for Form 1.
The XRPD patterns of the polymorphs are shown overlaid in FIG. 1. The conversion of Form 2 to Form 1 with time in an aqueous slurry at ambient temperature is shown in FIG. 2. In the conversion of Form 2 to Form 1 the loss of a peak characteristic of Form 2 (labelled B) at around 18.4 degrees 2Theta, a marked reduction in intensity in the peak at around 7 degrees 2Theta (labelled A) and the appearance of a peak characteristic of Form 1 (labelled C) at around 18.9 degrees 2Theta are particularly noticeable.
The temperature dependence of Form 3 is shown in FIG. 4. The temperature was varied according to the profile shown in FIG. 5. From FIG. 4 it can be seen that Form 3 converts first to Form 2 over the temperature range 30-170xc2x0 C. and then converts to Form 1 over the temperature range 170-230xc2x0 C. In the conversion of Form 3 to Form 2 the division of one peak in the range 21-23 degrees 2Theta into two peaks within the same range and the shifting leftwards of the peak at around 18.6 degrees 2Theta to around 18.4 degrees 2Theta are particularly noticeable. In the conversion of Form 2 to Form 1 similar changes to those noted in the previous paragraph may be observed.
The differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) profiles of Form 1 are shown in FIG. 3. The profiles are characterised by a transition at around 280-300xc2x0 C. (typically close to 298xc2x0 C.) corresponding to an endothermic event in the DSC and chemical degradation in the TGA. The DSC profiles of Forms 2 and 3 were not materially different under the conditions of the experiments performed and thus DSC is not a suitable technique for distinguishing between the 3 Forms. In FIG. 3 the absence of activity in the TGA and DSC profiles below around 298xc2x0 C. implies that the substance shows good physical and chemical stability at normal operating temperatures.
As shown in the Examples, enthalpy of dissolution of Forms 1 and 3 have been determined in certain organic solvents and accordingly an enthalpy of transition from Form 3 to Form 1 of 5.1-6.7 kJ/mol has been estimated.
Thus we prefer compound of formula (I) in unsolvated Form 1 since this form appears to be thermodynamically most stable at ambient temperature and also appears to be least susceptible to undesirable moisture sorption (see results in Examples section).
Although use of a compound of formula (I) in solvated form is not preferred, nevertheless we have surprisingly found that certain solvate forms have particularly attractive physicochemical properties which makes them useful as intermediates in the preparation of a compound of formula (I) in unsolvated form (eg by removal of solvent as a final step). For example we have discovered that certain stoichiometric solvates can be isolated as solids in highly crystalline form. Thus we also provide as an aspect of the invention:
Compound of formula (I) as the methylethylketone solvate
Compound of formula (I) as the isopropanol solvate
Compound of formula (I) as the tetrahydrofuran solvate
Compound of formula (I) as the acetone solvate.
In particular we provide the aforementioned solvates as solids in crystalline form.
A further particular advantage of these solvates is the fact that desolvation of the solvate (eg by heating) results in formation of the unsolvated form as the preferred Form 1. The aforementioned solvates have relatively low toxicity and are suitable for use in industrial scale manufacture. Compound of formula (I) as the DMF solvate which may also be isolated as a solid in crystalline form is also of interest for use in onward processing to unsolvated Form 1.
The compound of formula (I) and solvates thereof may be prepared by the methodology described hereinafter, constituting a further aspect of this invention.
A process according to the invention for preparing a compound of formula (I) comprises alkylation of a thioacid of formula (II) 
or a salt thereof.
In this process the compound of formula (II) may be reacted with a compound of formula FCH2L wherein L represents a leaving group (eg a halogen atom, a mesyl or tosyl group or the like) for example, an appropriate fluoromethyl halide under standard conditions. Preferably, the fluoromethyl halide reagent is bromofluoromethane.
As noted later, preferably the compound of formula (II) is employed as a salt, particularly the salt with diisopropylethylamine.
In a preferred process for preparing the compound of formula (I), the compound of formula (II) or a salt thereof is treated with bromofluoromethane optionally in the presence of a phase transfer catalyst. A preferred solvent is methylacetate, or more preferably ethylacetate, optionally in the presence of water. The presence of water improves solubility of both starting material and product and the use of a phase transfer catalyst results in an increased rate of reaction. Examples of phase transfer catalysts that may be employed include (but are not restricted to) tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltributylammonium bromide, benzyltributylammonium chloride, benzyltriethylammonium bromide, methyltributylammonium chloride and methyltrioctylammonium chloride. THF has also successfully been employed as solvent for the reaction wherein the presence of a phase transfer catalyst again provides a significantly faster reaction rate. Preferably the product present in an organic phase is washed firstly with aqueous acid eg dilute HCl in order to remove amine compounds such as triethylamine and diisopropylethylamine and then with aqueous base eg sodium bicarbonate in order to remove any unreacted precursor compound of formula (II). As noted later, if the compound of formula (I) so produced in solution in ethylacetate is distilled and toluene added, then unsolvated Form 1 crystallises out.
Compounds of formula (II) may be prepared from the corresponding 17xcex1-hydroxyl derivative of formula (III): 
using for example, the methodology described by G. H. Phillipps et al., (1994) Journal of Medicinal Chemistry, 37, 3717-3729. For example the step typically comprises the addition of a reagent suitable for performing the esterification eg an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride (employed in at least 2 times molar quantity relative to the compound of formula (III)) in the presence of an organic base eg triethylamine. The second mole of 2-furoyl chloride reacts with the thioacid moiety in the compound of formula (III) and needs to be removed eg by reaction with an amine such as diethylamine.
This method suffers disadvantages, however, in that the resultant compound of formula (II) is not readily purified of contamination with the by-product 2-furoyldiethylamide. We have therefore invented several improved processes for performing this conversion.
In a first such improved process we have discovered that by using a more polar amine such as diethanolamine, a more water soluble by-product is obtained (in this case 2-furoyldiethanolamide) which permits compound of formula (II) or a salt thereof to be produced in high purity since the by-product can efficiently be removed by water washing.
Thus according to this aspect of the invention we provide a process for preparing a compound of formula (II) which comprises:
(a) reacting a compound of formula (III) with an activated derivative of 2-furoic acid as in an amount of at least 2 moles of the activated derivative per mole of compound of formula (III) to yield a compound of formula (IIA); 
(b) removal of the sulphur-linked 2-furoyl moiety from compound of formula (IIA) by reaction of the product of step (a) with an organic primary or secondary amine base capable of forming a water soluble 2-furoyl amide.
In two particularly convenient embodiments of this process we also provide methods for the efficient purification of the end product which comprise either
(c1) when the product of step (b) is dissolved in a substantially water immiscible organic solvent, purifying the compound of formula (II) by washing out the amide by-product from step (b) with an aqueous wash, or
(c2) when the product of step (b) is dissolved in a water miscible solvent, purifying the compound of formula (II) by treating the product of step (b) with an aqueous medium so as to precipitate out pure compound of formula (II) or a salt thereof.
In step (a) preferably the activated derivative of 2-furoic acid may be an activated ester of 2-furoic acid, but is more preferably a 2-furoyl halide, especially 2-furoyl chloride. A suitable solvent for this reaction is ethylacetate or methylacetate (preferably methylacetate) (when step (c1) may be followed) or acetone (when step (c2) may be followed). Normally an organic base eg triethylamine will be present. In step (b) preferably the organic base is diethanolamine. The base may suitably be dissolved in a solvent eg methanol. Generally steps (a) and (b) will be performed at reduced temperature eg between 0 and 5xc2x0 C. In step (c1) the aqueous wash may be water, however the use of brine results in higher yields and is therefore preferred. In step (c2) the aqueous medium is for example a dilute aqueous acid such as dilute HCl.
According to a related aspect of the invention we provide an alternative process for preparing a compound of formula (II) which comprises:
(a) reacting a compound of formula (III) with an activated derivative of 2-furoic acid in an amount of at least 2 moles of activated derivative per mole of compound of formula (III) to yield a compound of formula (IIA); and
(b) removal of the sulphur-linked 2-furoyl moiety from compound of formula (IIA) by reaction of the product of step (a) with a further mole of compound of formula (III) to give two moles of compound of formula (II).
In step (a) preferably the activated derivative of 2-furoic acid may be an activated ester of 2-furoic acid, but is more preferably a 2-furoyl halide, especially 2-furoyl chloride. A suitable solvent for his step is acetone. Normally an organic base eg triethylamine will be present. In step (b) a suitable solvent is DMF or dimethylacetamide. Normally an organic base eg triethylamine will be present. Generally steps (a) and (b) will be performed at reduced temperature eg between 0 and 5xc2x0 C. The product may be isolated by treatment with acid and washing with water.
This aforementioned process is very efficient in that it does not produce any furoylamide by-product (thus affording inter alia environmental advantages) since the excess mole of furoyl moiety is taken up by reaction with a further mole of compound of formula (II) to form an additional mole of compound of formula (II).
Further general conditions for the conversion of compound of formula (III) to compound of formula (II) in the two processes just described will be well known to persons skilled in the art.
According to a preferred set of conditions, however, we have found that the compound of formula (II) may advantageously be isolated in the form of a solid crystalline salt. The preferred salt is a salt formed with a base such as triethylamine, 2,4,6-trimethylpyridine, diisopropylethylamine or N-ethylpiperidine. Such salt forms of compound of formula (II) are more stable, more readily filtered and dried and can be isolated in higher purity than the free thioacid. The most preferred salt is the salt formed with diisopropylethylamine. The triethylamine salt is also of interest.
Compounds of formula (III) may be prepared in accordance with procedures described in GB 2088877B.
Compounds of formula (III) may also be prepared by a process comprising the following steps: 
Step (a) comprises oxidation of a solution containing the compound of formula (V). Preferably, step (a) will be performed in the presence of a solvent comprising methanol, water, tetrahydrofuran, dioxan or diethylene glygol dimethylether. So as to enhance yield and throughput, preferred solvents are methanol, water or tetrahydrofuran, and more preferably are water or tetrahydrofuran, especially water and tetrahydrofuran as solvent. Dioxan and diethylene glygol dimethylether are also preferred solvents which may optionally (and preferably) be employed together with water. Preferably, the solvent will be present in an amount of between 3 and 10 vol relative to the amount of the starting material (1 wt.), more preferably between 4 and 6 vol., especially 5 vol. Preferably the oxidising agent is present in an amount of 1-9 molar equivalents relative to the amount of the starting material. For example, when a 50% w/w aqueous solution of periodic acid is employed, the oxidising agent may be present in an amount of between 1.1 and 10 wt. relative to the amount of the starting material (1 wt.), more preferably between 1.1 and 3 wt., especially 1.3 wt. Preferably, the oxidation step will comprise the use of a chemical oxidising agent. More preferably, the oxidising agent will be periodic acid or iodic acid or a salt thereof. Most preferably, the oxidising agent will be periodic acid or sodium periodate, especially periodic acid. Alternatively (or in addition), it will also be appreciated that the oxidation step may comprise any suitable oxidation reaction, eg one which utilises air and/or oxygen. When the oxidation reaction utilises air and/or oxygen, the solvent used in said reaction will preferably be methanol. Preferably, step (a) will involve incubating the reagents at room temperature or a little warmer, say around 25xc2x0 C. eg for 2 hours. The compound of formula (IV) may be isolated by recrystallisation from the reaction mixture by addition of an anti-solvent. A suitable anti-solvent for compound of formula (IV) is water. Surprisingly we have discovered that it is highly desirable to control the conditions under which the compound of formula (IV) is precipitated by addition of anti-solvent eg water. When the recrystallisation is performed using chilled water (eg water/ice mixture at a temperature of 0-5xc2x0 C.) although better anti-solvent properties may be expected we have found that the crystalline product produced is very voluminous, resembles a soft gel and is very difficult to filter. Without being limited by theory we believe that this low density product contains a large amount of solvated solvent within the crystal lattice. By contrast when conditions of around 10xc2x0 C. or higher are used (eg around ambient temperature) a granular product of a sand like consistency which is very easily filtered is produced. Under these conditions, crystallisation typically commences after around 1 hour and is typically completed within a few hours (eg 2 hours). Without being limited by theory we believe that this granular product contains little or no solvated solvent within the crystal lattice.
Step (b) will typically comprise the addition of a reagent suitable for converting a carboxylic acid to a carbothioic acid eg using hydrogen sulphide gas together with a suitable coupling agent eg carbonyldiimidazole (CDI) in the presence of a suitable solvent eg dimethylformamide.
An alternative process for preparing a compound of formula (II) comprises treating a compound of formula (X) with a reagent suitable for converting a carboxylic acid to a carbothioic acid eg using hydrogen sulphide gas together with a suitable coupling agent such as CDI in the presence of a suitable solvent eg DMF. Compounds of formula (X) may be prepared by methodology analogous to that described herein.
An alternative process for preparing a compound of formula (I) or a solvate thereof comprises reacting a compound of formula (VI) 
with a fluorine source.
Examples of suitable sources of fluorine include fluoride (eg sodium fluoride) or, more preferably, HF. The preferred reagent is aqueous HF. A solvent such as THF or DMF may be employed.
A compound of formula (VI) may be prepared by a process comprising
(a) alkylating a compound of formula (VII) 
xe2x80x83or a salt thereof;
(b) reacting a compound of formula (VIII) 
xe2x80x83with an epoxide forming reagent; or
(c) esterifying a compound of formula (IX) 
In process (a), analogous conditions to those described above for the conversion of a compound of formula (II) to a compound of formula (I) may be employed. Typically compound of formula (VII) will be reacted with a compound of formula FCH2L wherein L represents a leaving group (eg a halogen atom, a mesyl or tosyl group or the like) for example, an appropriate fluoromethyl halide under standard conditions. Preferably, the fluoromethyl halide reagent is bromofluoromethane.
Process (b) is preferably performed in two steps: (i) formation of a halohydrin especially a bromohydrin (eg by reaction with bromodan or equivalent reagent), followed by (ii) treatment with base such as sodium hydroxide so as to effect ring closure. The product of step (i) is a compound of formula (IXA) which is a novel intermediate that may be isolated, if desired: 
wherein X represents halogen, especially Br.
In process (c), a suitable reagent would be an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride in the presence of an organic base eg triethylamine. This reaction may be performed at elevated temperature eg around 60xc2x0 C. or else at ambient temperature in the presence of an acylation catalyst eg dimethylamino pyridine (DMAP).
Compounds of formula (VII) may be prepared by a process comprising esterification of a compound of formula (XI) 
Analogous conditions to those described above for the conversion of a compound of formula (III) to a compound of formula (II) may be employed. For example, a suitable reagent would be an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride in the presence of an organic base eg triethylamine. Compound of formula (XI) is known (J Labelled Compd Radiopharm (1997) 39(7) 567-584).
A compound of formula (VIII) may be prepared by a process comprising
(a) alkylating a compound of formula (XII) 
xe2x80x83or a salt thereof; or
(b) esterifying a compound of formula (XIII) 
In process (a), analogous conditions to those described above for the conversion of a compound of formula (II) to a compound of formula (I) may be employed. Typically compound of formula (XII) will be reacted with a compound of formula FCH2L wherein L represents a leaving group (eg a halogen atom, a mesyl or tosyl group or the like) for example, an appropriate fluoromethyl halide under standard conditions. Preferably, the fluoromethyl halide reagent is bromofluoromethane.
In process (b), analogous conditions to those employed above for the conversion of a compound of formula (IX) to a compound of formula (VI) may be employed. For example, a suitable reagent would be an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride in the presence of an organic base eg triethylamine.
Compounds of formula (IX) and (XIII) may be prepared by alkylating the corresponding thioacids (XI) and (XIV) (defined below) using methodology analogous to that already described (eg by reaction with a compound of formula FCH2L wherein L represents a leaving group (eg a halogen atom, a mesyl or tosyl group or the like) for example, an appropriate fluoromethyl halide under standard conditions. Preferably, the fluoromethyl halide reagent is bromofluoromethane. The thioacid (XI) is a known compound (J Labelled Compd Radiopharm (1997) 39(7) 567-584).
Compound of formula (XII) may be prepared by a process comprising esterifying a compound of formula (XIV): 
or a salt thereof.
This process may be performed using methodology analogous to that already described. For example, a suitable reagent would be an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride in the presence of an organic base eg triethylamine.
Compounds of formula (XIV) may be prepared from the corresponding carboxylic acid eg by a process analogous to that described above for the conversion of a compound of formula (IV) to a compound of formula (III). The aforesaid corresponding carboxylic acid is known (Upjohn, WO 90/15816).
A further alternative process for preparing a compound of formula (I) or a solvate thereof comprises deprotecting or unmasking a compound of formula (I) in which the 11-xcex2-hydroxy group is protected or masked. A first such process comprises deprotecting a compound of formula (XV) 
wherein P represents a hydroxy protecting group.
Examples of hydroxy protecting groups P are described in Protective Groups in Organic Chemistry Ed J F W McOmie (Plenum Press 1973) or Protective Groups in Organic Synthesis by Theodora W Green (John Wiley and Sons, 1991).
Examples of suitable hydroxy protecting groups P include groups selected from carbonate, alkyl (eg t-butyl or methoxymethyl), aralkyl (eg benzyl, p-nitrobenzyl, diphenylmethyl or triphenylmethyl), heterocyclic groups such as tetrahydropyranyl, acyl (eg acetyl or benzyl) and silyl groups such as trialkylsilyl (eg t-butyldimethylsilyl). The hydroxy protecting groups may be removed by conventional techniques. Thus, for example, carbonate may be removed by treatment with base and alkyl, silyl, acyl and heterocyclic groups may be removed by solvolysis eg by hydrolysis under acid or basic conditions. Aralkyl groups such as triphenylmethyl may similarly be removed by solvolysis eg by hydrolysis under acidic conditions. Aralkyl groups such as benzyl or p-nitrobenzyl may be cleaved by hydrogenolysis in the presence of a Noble metal catalyst such as palladium on charcoal. p-Nitrobenzyl may also be cleaved by photolysis.
The 11-xcex2-hydroxy group may be masked as a carbonyl group. Thus a second such process comprises reduction of a compound of formula (XVI) 
Reduction to the compound of formula (I) may be achieved eg by treatment with a hydride reducing agent such as borohydride eg sodium borohydride.
The 11-ketone (XVI) may also be masked. Examples of masked derivatives of compound of formula (XVI) include (i) ketal derivatives eg ketals formed by treatment of the compound of formula (XVI) with an alcohol eg methanol, ethanol or ethan-1,2-diol, (ii) dithioketal derivatives eg dithioketals formed by treatment of the compound of formula (XVI) with a thiol eg methanethiol, ethanethiol or ethan-1,2-dithiol, (iii) monothioketal derivatives eg monothioketals formed by treatment of the compound of formula (XVI) with eg 1-hydroxy-ethane-2-thiol, (iv) derivatives formed by treatment of the compound of formula (XVI) with an alcoholamine eg ephedrine, (v) imines formed by treatment of the compound of formula (XVI) with amines, (vi) oximes formed by treatment of compounds of formula (XVI) with hydroxylamines. We claims such derivatives of compound of formula (XVI) as an aspect of the invention.
These masked derivatives may be converted back to the ketone by conventional means eg ketals, imines and oximes are converted to carbonyl by treatment with dilute acid and dithioketals are converted to the ketone by a variety of methods as described by P. C. Bulman Page et al (1989), Tetrahedron, 45, 7643-7677 and references therein.
Compounds of formula (XV) may be prepared by a process comprising
(a) alkylating a compound of formula (XVII) 
xe2x80x83or a salt thereof wherein P represents a hydroxy protecting group; or
(b) esterifying a compound of formula (XVIII) 
In step (a), analogous conditions to those described above for the conversion of a compound of formula (II) to a compound of formula (I) may be employed. Typically compound of formula (XVII) will be reacted with a compound of formula FCH2L wherein L represents a leaving group (eg a halogen atom, a mesyl or tosyl group or the like) for example, an appropriate fluoromethyl halide under standard conditions. Preferably, the fluoromethyl halide reagent is bromofluoromethane.
In step (b), analogous conditions to those employed above for the conversion of a compound of formula (IX) to a compound of formula (VI) may be employed. For example, a suitable reagent would be an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride in the presence of an organic base eg triethylamine.
Compound of formula (XVIII) may be prepared by alkylating the corresponding thioacid using methodology analogous to that already described (eg by reaction with a compound of formula FCH2L wherein L represents a leaving group (eg a halogen atom, a mesyl or tosyl group or the like) for example, an appropriate fluoromethyl halide under standard conditions. Preferably, the fluoromethyl halide reagent is bromofluoromethane. The corresponding thioacids are known compounds or may be prepared by standard methodology. Compound of formula (XVIII) may alternatively be prepared by protection of the corresponding hydroxy derivative.
Compound of formula (XVII) may be prepared by a process comprising esterifying a compound of formula (XIX) 
or a salt thereof wherein P represents a hydroxy protecting group.
This process may be performed using methodology analogous to that already described for the conversion of compounds of formula (III) to (II). For example, a suitable reagent would be an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride in the presence of an organic base eg triethylamine.
Compounds of formula (XIX) may be prepared by protecting the corresponding hydroxy derivative (III), having first protected the thioacid which would then be deprotected.
Compounds of formula (XVI) may be prepared by a process comprising
(a) alkylating a compound of formula (XX) 
xe2x80x83or a salt thereof or a derivative wherein the 11-carbonyl group is masked; or
(b) esterifying a compound of formula (XXI) 
xe2x80x83or a derivative wherein the 11-carbonyl group is masked.
In step (a), analogous conditions to those described above for the conversion of a compound of formula (III) to a compound of formula (II) may be employed. Typically compound of formula (XX) will be reacted with a compound of formula FCH2L wherein L represents a leaving group (eg a halogen atom, a mesyl or tosyl group or the like) for example, an appropriate fluoromethyl halide under standard conditions. Preferably, the fluoromethyl halide reagent is bromofluoromethane.
In step (b), analogous conditions to those employed above for the conversion of a compound of formula (IX) to a compound of formula (VI) may be employed. For example, a suitable reagent would be an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride in the presence of an organic base eg triethylamine.
Compound of formula (XXI) or a derivative thereof wherein the 11-ketone group is masked may be prepared by alkylating the corresponding thioacid using methodology analogous to that already described (eg by reaction with a compound of formula FCH2L wherein L represents a leaving group (eg a halogen atom, a mesyl or tosyl group or the like) for example, an appropriate fluoromethyl halide under standard conditions. Preferably, the fluoromethyl halide reagent is bromofluoromethane. The corresponding thioacids are known compounds or may be prepared from the corresponding carboxylic acids by methods analogous to those previously described.
Compound of formula (XX) may be prepared by a process comprising esterifying a compound of formula (XXII) 
or a derivative thereof wherein the 11-ketone group is masked.
This process may be performed using methodology analogous to that already described. For example, a suitable reagent would be an activated derivative of 2-furoic acid such as an activated ester or preferably a 2-furoyl halide eg 2-furoyl chloride in the presence of an organic base eg triethylamine.
Compounds of formula (XXII) and derivatives thereof wherein the 11-ketone is masked may be prepared by oxidation of the corresponding hydroxy derivative (IV) followed by masking of the ketone and subsequent conversion of the carboxylic acid group to the thioacid (see eg conversion of compounds of formula (IV) to (III).
A further alternative process for the preparation of compounds of formula (I) or a solvate thereof comprises reaction of a compound of formula (XXIII) 
wherein L represents a leaving group (eg halide other than fluoride such as chloride, iodide or a sulphonate ester such mesylate, tosylate, triflate) with a fluorine source.
Preferably the fluorine source is fluoride ion eg KF. Further details for this conversion may be obtained by reference to G. H. Phillipps et al., (1994) Journal of Medicinal Chemistry, 37, 3717-3729 or J Labelled Compd Radiopharm (1997) 39(7) 567-584).
Compounds of formula (XXIII) may be prepared by methods analogous to those described herein. Corresponding novel intermediates of formula (VI), (VIII), (IX), (IXA), (XV) and (XVI) wherein the xe2x80x94CH2F moiety is replaced with a xe2x80x94CH2L moiety (wherein L represents a leaving group other than fluorine) are claimed as an aspect of the invention.
A further alternative process for the preparation of compounds of formula (I) or a solvate thereof comprises deprotection or unmasking of a derivative of a compound of formula (I) in which the 3-carbonyl group is protected or masked.
The 3-carbonyl group may be masked in a manner analogous to that described above in relation to masking of the 11-carbonyl position. Thus the 3-carbonyl may be masked eg as a ketal, monothioketal, dithioketal, derivative with an alcoholamine, oxime or imine. The carbonyl group may be recovered by conventional means eg ketals are converted to carbonyl by treatment with dilute acid and dithioketals are converted to the ketone by a variety of methods as described by P. C. Bulman Page et al (1989), Tetrahedron, 45, 7643-7677 and references therein.
Certain intermediate compounds are new and we provide these, together where appropriate with their salts and solvates, as an aspect of the invention.
As noted above, we provide as a particular aspect of the invention a process for preparing a compound of formula (I) in unsolvated form which comprises:
(a) Crystallising the compound of formula (I) in the presence of a non-solvating solvent such as ethanol, methanol, water, ethyl acetate, toluene, methylisobutylketone or mixtures thereof; or
(b) Desolvating a compound of formula (I) in solvated form (eg in the form of a solvate with acetone, isopropanol, methylethylketone, DMF or tetrahydrofuran) eg by heating.
In step (b) the desolvation will generally be performed at a temperature exceeding 50xc2x0 C. preferably at a temperature exceeding 100xc2x0 C. Generally heating will be performed under vacuum.
There is also provided a compound of formula (I) in unsolvated form obtainable by the aforementioned process.
There is also provided as a particular aspect of the invention a process for preparing a compound of formula (I) as unsolvated Form 1 polymorph which comprises dissolving compound of formula (I) in methylisobutylketone, ethyl acetate or methyl acetate and producing compound of formula (I) as unsolvated Form 1 by addition of a non-solvating anti-solvent such as iso-octane or toluene.
According to a first preferred embodiment of this process the compound of formula (I) may be dissolved in ethyl acetate and compound of formula (I) as unsolvated Form 1 polymorph may be obtained by addition of toluene as anti-solvent. In order to improve the yield, preferably the ethyl acetate solution is hot and once the toluene has been added the mixture is distilled to reduce the content of ethyl acetate.
According to a second preferred embodiment of this process the compound of formula (I) may be dissolved in methylisobutylketone and compound of formula (I) as unsolvated Form 1 polymorph may be obtained by addition of isooctane as anti-solvent.
There is also provided a compound of formula (I) as unsolvated Form 1 polymorph obtainable by the aforementioned processes.
A process for preparing a compound of formula (I) as unsolvated Form 2 polymorph comprises dissolving compound of formula (I) in unsolvated form in methanol or dry dichloromethane and recrystallising the compound of formula (I) as unsolvated Form 2 polymorph. Typically the compound of formula (I) will be dissolved in hot in methanol or dry dichloromethane and allowed to cool.
There is also provided a compound of formula (I) as unsolvated Form 2 polymorph obtainable by the aforementioned process.
A process for preparing a preparing a compound of formula (I) as unsolvated Form 3 polymorph comprises dissolving compound of formula (I) in particular as the acetone solvate in dichloromethane in the presence of water (typically 1-3% water by volume) and recrystallising the compound of formula (I) as unsolvated Form 3 polymorph.
There is also provided a compound of formula (I) as unsolvated Form 3 polymorph obtainable by the aforementioned process.
The advantages of the compound of formula (I) and/or its solvates or polymorphs may include the fact that the substance appears to demonstrate excellent anti-inflammatory properties, with predictable pharmacokinetic and pharmacodynamic behaviour, with an attractive side-effect profile, long duration of action, and is compatible with a convenient regime of treatment in human patients, in particular being amendable to once-per day dosing. The advantages may be appreciated in particular when the compound of formula (I) and/or its solvates or polymorphs are employed in combination with a the long-acting xcex22-adrenoreceptor agonist. Further advantages may include the fact that the substance has desirable physical and chemical properties which allow for ready manufacture and storage.